Class SplineUtility

A collection of methods for extracting information about Spline types.

Inheritance

Object

SplineUtility

Namespace: UnityEngine.Splines

Syntax

public static class SplineUtility : object

Fields

DrawResolutionDefault

The default resolution used when unrolling a curve to draw a preview in the Scene View.

Pick resolution is used when determining how many segments are required to unroll a curve. Unrolling is the process of calculating a series of line segments to approximate a curve. Some functions in SplineUtility allow you to specify a resolution. Lower resolution means fewer segments, while higher resolutions result in more segments. Use lower resolutions where performance is critical and accuracy is not paramount. Use higher resolution where a fine degree of accuracy is necessary and performance is less important.

Declaration

public const int DrawResolutionDefault = null

Field Value

Type	Description
Int32

PickResolutionDefault

The default resolution used when unrolling a curve to hit test while picking (selecting a spline with a cursor).

Pick resolution is used when determining how many segments are required to unroll a curve. Unrolling is the process of calculating a series of line segments to approximate a curve. Some functions in SplineUtility allow you to specify a resolution. Lower resolution means fewer segments, while higher resolutions result in more segments. Use lower resolutions where performance is critical and accuracy is not paramount. Use higher resolution where a fine degree of accuracy is necessary and performance is less important.

Declaration

public const int PickResolutionDefault = null

Field Value

Type	Description
Int32

PickResolutionMax

The maximum resolution allowed when unrolling a curve to hit test while picking (selecting a spline with a cursor).

Pick resolution is used when determining how many segments are required to unroll a curve. Unrolling is the process of calculating a series of line segments to approximate a curve. Some functions in SplineUtility allow you to specify a resolution. Lower resolution means fewer segments, while higher resolutions result in more segments. Use lower resolutions where performance is critical and accuracy is not paramount. Use higher resolution where a fine degree of accuracy is necessary and performance is less important.

Declaration

public const int PickResolutionMax = null

Field Value

Type	Description
Int32

PickResolutionMin

The minimum resolution allowable when unrolling a curve to hit test while picking (selecting a spline with a cursor).

Pick resolution is used when determining how many segments are required to unroll a curve. Unrolling is the process of calculating a series of line segments to approximate a curve. Some functions in SplineUtility allow you to specify a resolution. Lower resolution means fewer segments, while higher resolutions result in more segments. Use lower resolutions where performance is critical and accuracy is not paramount. Use higher resolution where a fine degree of accuracy is necessary and performance is less important.

Declaration

public const int PickResolutionMin = null

Field Value

Type	Description
Int32

Methods

CalculateLength<T>(T, float4x4)

Calculate the length of a spline when transformed by a matrix.

Declaration

public static float CalculateLength<T>(this T spline, float4x4 transform)
    where T : ISpline

Parameters

Type	Name	Description
T	spline
float4x4	transform

Returns

Type	Description
Single

Type Parameters

Name	Description
T	A type implementing ISpline.

ConvertIndexUnit<T>(T, Single, PathIndexUnit)

Given a normalized interpolation ratio, calculate the associated interpolation value in another targetPathUnit regarding a specific spline.

Declaration

public static float ConvertIndexUnit<T>(this T spline, float t, PathIndexUnit targetPathUnit)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The Spline to use for the conversion, this is necessary to compute Normalized and Distance PathIndexUnits.
Single	t	Normalized interpolation ratio (0 to 1).
PathIndexUnit	targetPathUnit	The PathIndexUnit to which 't' should be converted.

Returns

Type	Description
Single	The interpolation value converted to targetPathUnit.

Type Parameters

Name	Description
T	A type implementing ISpline.

ConvertIndexUnit<T>(T, Single, PathIndexUnit, PathIndexUnit)

Given an interpolation value using a certain PathIndexUnit type, calculate the associated interpolation value in another targetPathUnit regarding a specific spline.

Declaration

public static float ConvertIndexUnit<T>(this T spline, float t, PathIndexUnit fromPathUnit, PathIndexUnit targetPathUnit)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The Spline to use for the conversion, this is necessary to compute Normalized and Distance PathIndexUnits.
Single	t	Interpolation in the original PathIndexUnit.
PathIndexUnit	fromPathUnit	The PathIndexUnit for the original interpolation value.
PathIndexUnit	targetPathUnit	The PathIndexUnit to which 't' should be converted.

Returns

Type	Description
Single	The interpolation value converted to targetPathUnit.

Type Parameters

Name	Description
T	A type implementing ISpline.

CurveToSplineT<T>(T, Single)

Given an interpolation value for a curve, calculate the relative normalized spline interpolation.

Declaration

public static float CurveToSplineT<T>(this T spline, float curve)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The target spline.
Single	curve	A curve index and normalized interpolation. The curve index is represented by the integer part of the float, and interpolation is the fractional part. This is the format used by Knot.

Returns

Type	Description
Single	An interpolation value relative to normalized Spline length (0 to 1).

Type Parameters

Name	Description
T	A type implementing ISpline.

See Also

SplineToCurveT<T>(T, Single, out Single)

Evaluate<T>(T, Single, out float3, out float3, out float3)

Compute interpolated position, direction and upDirection at ratio t. Calling this method to get the 3 vectors is faster than calling independently EvaluatePosition, EvaluateDirection and EvaluateUpVector for the same time t as it reduces some redundant computation.

Declaration

public static bool Evaluate<T>(this T spline, float t, out float3 position, out float3 tangent, out float3 upVector)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.
float3	position	Output variable for the float3 position at t.
float3	tangent	Output variable for the float3 tangent at t.
float3	upVector	Output variable for the float3 up direction at t.

Returns

Type	Description
Boolean	Boolean value, true if a valid set of output variables as been computed.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluateAcceleration<T>(T, Single)

Return an interpolated acceleration at ratio t.

Declaration

public static float3 EvaluateAcceleration<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.

Returns

Type	Description
float3	An acceleration on the spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluateCurvature<T>(T, Single)

Return an interpolated curvature at ratio t.

Declaration

public static float EvaluateCurvature<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.

Returns

Type	Description
Single	A curvature on the spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluateCurvatureCenter<T>(T, Single)

Return the curvature center at ratio t. The curvature center represents the center of the circle that is tangent to the curve at t. This circle is in the plane defined by the curve velocity (tangent) and the curve acceleration at that point.

Declaration

public static float3 EvaluateCurvatureCenter<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.

Returns

Type	Description
float3	A point representing the curvature center associated to the position at t on the spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluatePosition<T>(T, Single)

Return an interpolated position at ratio t.

Declaration

public static float3 EvaluatePosition<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.

Returns

Type	Description
float3	A position on the spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluateTangent<T>(T, Single)

Return an interpolated direction at ratio t.

Declaration

public static float3 EvaluateTangent<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline to interpolate.
Single	t	A value between 0 and 1 representing the ratio along the curve.

Returns

Type	Description
float3	A direction on the spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

EvaluateUpVector<T>(T, Single)

Evaluate an up vector of a spline at a specific t

Declaration

public static float3 EvaluateUpVector<T>(this T spline, float t)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The NativeSpline to evaluate.
Single	t	A value between 0 and 1 representing a percentage of the curve.

Returns

Type	Description
float3	An up vector

Type Parameters

Name	Description
T	A type implementing ISpline.

GetBounds<T>(T)

Calculate the bounding box of a Spline.

Declaration

public static Bounds GetBounds<T>(this T spline)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The spline for which to calculate bounds.

Returns

Type	Description
Bounds	The bounds of a spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

GetNearestPoint<T>(T, float3, out float3, out Single, Int32, Int32)

Calculate the point on a spline nearest to a point.

Declaration

public static float GetNearestPoint<T>(T spline, float3 point, out float3 nearest, out float t, int resolution = null, int iterations = 2)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The input spline to search for nearest point.
float3	point	The input point to compare.
float3	nearest	The point on a spline nearest to the input point. The accuracy of this value is affected by the resolution.
Single	t	The normalized interpolation ratio corresponding to the nearest point.
Int32	resolution	Affects how many segments to split a spline into when calculating the nearest point. Higher values mean smaller and more segments, which increases accuracy at the cost of processing time. The minimum resolution is defined by PickResolutionMin, and the maximum is defined by PickResolutionMax. In most cases, the default resolution is appropriate. Use with to fine tune point accuracy.
Int32	iterations	The nearest point is calculated by finding the nearest point on the entire length of the spline using to divide into equally spaced line segments. Successive iterations will then subdivide further the nearest segment, producing more accurate results. In most cases, the default value is sufficient, but if extreme accuracy is required this value can be increased to a maximum of PickResolutionMax.

Returns

Type	Description
Single	The distance from input point to nearest point on spline.

Type Parameters

Name	Description
T	A type implementing ISpline.

GetNearestPoint<T>(T, Ray, out float3, out Single, Int32, Int32)

Calculate the point on a spline nearest to a ray.

Declaration

public static float GetNearestPoint<T>(T spline, Ray ray, out float3 nearest, out float t, int resolution = null, int iterations = 2)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The input spline to search for nearest point.
Ray	ray	The input ray to search against.
float3	nearest	The point on a spline nearest to the input ray. The accuracy of this value is affected by the resolution.
Single	t	The normalized time value to the nearest point.
Int32	resolution	Affects how many segments to split a spline into when calculating the nearest point. Higher values mean smaller and more segments, which increases accuracy at the cost of processing time. The minimum resolution is defined by PickResolutionMin, and the maximum is defined by PickResolutionMax. In most cases, the default resolution is appropriate. Use with to fine tune point accuracy.
Int32	iterations	The nearest point is calculated by finding the nearest point on the entire length of the spline using to divide into equally spaced line segments. Successive iterations will then subdivide further the nearest segment, producing more accurate results. In most cases, the default value is sufficient, but if extreme accuracy is required this value can be increased to a maximum of PickResolutionMax.

Returns

Type	Description
Single	The distance from ray to nearest point.

Type Parameters

Name	Description
T	A type implementing ISpline.

GetNormalizedInterpolation<T>(T, Single, PathIndexUnit)

Given an interpolation value in any PathIndexUnit type, calculate the normalized interpolation ratio value relative to a Spline.

Declaration

public static float GetNormalizedInterpolation<T>(T spline, float t, PathIndexUnit originalPathUnit)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The Spline to use for the conversion, this is necessary to compute Normalized and Distance PathIndexUnits.
Single	t	The 't' value to normalize in the original PathIndexUnit.
PathIndexUnit	originalPathUnit	The PathIndexUnit from the original 't'.

Returns

Type	Description
Single	The normalized interpolation ratio (0 to 1).

Type Parameters

Name	Description
T	A type implementing ISpline.

GetPointAtLinearDistance<T>(T, Single, Single, out Single)

Given a Spline and interpolation ratio, calculate the 3d point at a linear distance from point at spline.EvaluatePosition(t). Returns the corresponding time associated to this 3d position on the Spline.

Declaration

public static float3 GetPointAtLinearDistance<T>(this T spline, float fromT, float relativeDistance, out float resultPointT)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The Spline on which to compute the point.
Single	fromT	The Spline interpolation ratio 't' (normalized) from which the next position need to be computed.
Single	relativeDistance	The relative distance at which the new point should be placed. A negative value will compute a point at a 'resultPointTime' previous to 'fromT' (backward search).
Single	resultPointT	The normalized interpolation ratio of the resulting point.

Returns

Type	Description
float3	The 3d point from the spline located at a linear distance from the point at t.

Type Parameters

Name	Description
T	A type implementing ISpline.

GetSegmentCount(Single, Int32)

Use this function to calculate the number of segments for a given spline length and resolution.

Declaration

public static int GetSegmentCount(float length, int resolution)

Parameters

Type	Name	Description
Single	length	A distance value in PathIndexUnit.
Int32	resolution	A value used to calculate the number of segments for a length. This is calculated as max(MIN_SEGMENTS, min(MAX_SEGMENTS, sqrt(length) * resolution)).

Returns

Type	Description
Int32	The number of segments as calculated for given length and resolution.

SetPivot(SplineContainer, Vector3)

Reset a transform position to a position while keeping knot positions in the same place. This modifies both knot positions and transform position.

Declaration

public static void SetPivot(SplineContainer container, Vector3 position)

Parameters

Type	Name	Description
SplineContainer	container	The target spline.
Vector3	position	The

SplineToCurveT<T>(T, Single, out Single)

Given a normalized interpolation (t) for a spline, calculate the curve index and curve-relative normalized interpolation.

Declaration

public static int SplineToCurveT<T>(this T spline, float splineT, out float curveT)
    where T : ISpline

Parameters

Type	Name	Description
T	spline	The target spline.
Single	splineT	A normalized spline interpolation value to be converted into curve space.
Single	curveT	A normalized curve interpolation value.

Returns

Type	Description
Int32	The curve index.

Type Parameters

Name	Description
T	A type implementing ISpline.